Prevention of HIV-1 infection to reduce the number of newly infected patients is an international priority. Various modalities such as male circumcision, prophylactic HIV vaccines, vaginal microbicides and oral pre-exposure prophylaxis have been explored to prevent sexual contraction of HIV. Prevention of HIV infection by using anti-viral agents as vaginal microbicides has received more attention in recent years.
Worldwide, nearly half of all individuals living with HIV are now women, who acquire the virus largely by heterosexual exposure. Many women, because of limited economic options and gender inequality, cannot reliably negotiate sexual encounters, leaving them vulnerable to unwanted pregnancy and sexually transmitted infections (STIs), including HIV. In the absence of an effective vaccine, topical microbicide formulations, which are applied vaginally or rectally, represent an attractive solution to stop HIV transmission. However, clinical trials focusing on vaginal prophylaxis of HIV using topical microbicides have shown mixed results. Several topical microbicides such as BufferGel™, PRO 2000, and Carraguard™ have failed to show efficacy in clinical trials whereas coitally-dependent administration of 1% tenofovir gel has shown success. Conversely, the VOICE trial employing a coitus-independent, once daily administration of 1% tenofovir gel was halted due to lack of efficacy. The VOICE trial setback has prompted investigators to examine alternatives. Therefore, there is a need for new anti-viral gels that provide sustained delivery of anti-viral therapy for the prevention of sexual HIV transmission but can be used coitally-independent.